Brendelberger, Stefan

Sattler, Christian

Thomas, Louis

Institute of Transport Research:Publications

THIS PROJECT HAS RECEIVED FUNDING FROM THE EUROPEAN UNION’S HORIZON 2020 RESEARCH AND INNOVATION PROGRAMME UNDER GRANT AGREEMENT NO 823802SFERA-IIISolar Facilities for the European Research Area4th Doctoral ColloquiumCologne, Germany, September 11th-13th 2023Development of a Redox Material Assembly for Solar Thermochemical Fuel ProductionLouis Thomas, DLR Institute of Future Fuelslouis.thomas@dlr.deNETWORKINGExaminer: Prof. Dr. Christian SattlerSupervisor: Dr.-Ing. Stefan BrendelbergerLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023Overview1234MotivationModeling ApproachFirst ResultsSummary and Outlook2Solar Fuel ProductionThermochemical Redox CycleLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023𝑪𝒆𝑶𝟐𝒓𝒆𝒅𝒖𝒄𝒕𝒊𝒐𝒏𝑪𝒆𝑶𝟐−𝜹 +𝜹𝟐𝑶𝟐𝑪𝒆𝑶𝟐 + 𝜹𝑯𝟐/𝑪𝑶𝒐𝒙𝒊𝒅𝒂𝒕𝒊𝒐𝒏𝑪𝒆𝑶𝟐−𝜹 + 𝜹𝑯𝟐𝑶/𝑪𝑶𝟐𝑶𝟐𝑯𝟐𝑶𝑪𝑶𝟐Concentrated Solar Radiation𝑯𝟐 /𝑪𝑶 as solar fuels / syngasDLR, CC BY-NC-ND 3.03𝑻 𝒑𝑶𝟐Louis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023▪ Redox material: Ceria RPC (reticulated porous ceramic) structure▪ RPC blocks mounted at reactor cavity walls▪ Batch operation with temperature / pressure swing between reduction and oxidation stepS. Zoller, E. Koepf, D. Nizamian, M. Stephan, A. Patané, P. Haueter, M. Romero, J. González-Aguilar, D. Lieftink, E. de Wit, S. Brendelberger, A. Sizmann, and A. Steinfeld, Joule 6, 1606 (2022).State of the ArtReactor Concept and Redox Material4R2Mx ReactorReactor Features of MW-Scale VisionLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023▪ Separate reduction and oxidation reactor cavities▪ Receiver reactor cavity stays at high temperature, continuous on-sun operation▪ Multiple movable Redox Material Assembly (RMA) unitsS. Brendelberger, P. Holzemer-Zerhusen, E. Vega Puga, M. Roeb, and C. Sattler, Solar Energy 235, 118 (2022).5R2Mx ReactorProof-of-Concept Test RigLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023▪ Separate reactor cavities with cylindrical shape for practical implementation and manufacturing▪ Cylindrical Redox Material Assembly (RMA), which is moved between reduction and oxidation reactor via linear transport unit▪ Uniform thermal irradiation of RPC cylinder via electrical heating (no solar interface)Reduction reactorOxidation reactorRedox materialConnectorTransport unitGate6Modeling GoalRadiation Attenuation and Absorption in RPC CylinderLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023▪ Understanding the behavior of an RPC cylinder inside the R2Mx test-rig▪ Intensity attenuation and absorption characteristics in radial direction▪ Compare to flat RPC plate and collimated irradiationRPC Cylinder7Hot ReductionReactor CavityIntensity Attenuation of RadiationIn 𝐶𝑒𝑂2−𝛿 RPC StructureLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023Intensity attenuation in 𝐶𝑒𝑂2−𝛿 RPC structure (Beer-Lambert-Law):𝐼 𝑥𝐼0= exp −𝛽𝑥Extinction coefficient: 𝛽 ∝ϕ2𝑑𝑚[1] Mean pore diameter: 𝑑𝑚 ∝ϕ𝑛𝑝𝑝𝑖[1]RPC porosity: ϕPores per inch: 𝑛𝑝𝑝𝑖[1] S. Ackermann, M. Takacs, J. Scheffe, and A. Steinfeld, International Journal of Heat and Mass Transfer 107, 439 (2017).Analytical solutions8Absorption of RadiationIn 𝐶𝑒𝑂2−𝛿 RPC StructureLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023Radiation absorption of 𝐶𝑒𝑂2−𝛿 RPC structure:𝛼 = 1 − 𝑟 =Total hemispherical reflectivity:𝑟𝐶𝑒𝑂2−𝛿 𝛿, 𝑇 =𝑏𝛿+𝛿∗ 𝑎+ 𝑐 ∗ 𝛿 [2]Reduction extent: 𝛿 𝑇, 𝑝𝑂2Fitting parameters: 𝑎 𝑇 , 𝑏 𝑇 , 𝑐 𝑇For continuity (at 𝛿 = 0): 𝛿∗ = 10−10[2] S. Ackermann and A. Steinfeld, Solar Energy Materials and Solar Cells 159, 167 (2017).Operating range for𝑝𝑂2 = 0.001 𝑚𝑏𝑎𝑟9Modeling ApproachRPC Geometry and Irradiation TypeLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023xyz……∆𝑟xyz……∆𝑥Compare 4 modeling cases:1. RPC cylinder▪ Collimated irradiation▪ Diffuse irradiation2. RPC plate▪ Collimated irradiation▪ Diffuse irradiation10Model ImplementationMonte Carlo Simulation (Python)Louis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023Initiate rays at RPC surface with random interaction length and (normalized) direction:▪ 𝑟𝑎𝑦𝑝𝑜𝑠 = RPC surface▪ 𝑟𝑎𝑦𝑙𝑒𝑛𝑔𝑡ℎ = −ln(ም𝐼∈[0.0,1.0])𝛽▪ 𝑟𝑎𝑦𝑑𝑖𝑟, 𝑐𝑜𝑙𝑙 =100▪ 𝑟𝑎𝑦𝑑𝑖𝑟, 𝑑𝑖𝑓𝑓 =cos ෬𝑎 ∈ 0, 𝜋/2cos ෰𝑏 ∈ 0, 𝜋cos Ǎ𝑐 ∈ 0, 𝜋At new position rays are absorbed or reflected via statistical interaction:▪ 𝑟𝑎𝑦𝑝𝑜𝑠 = 𝑟𝑎𝑦𝑝𝑜𝑠 + 𝑟𝑎𝑦𝑙𝑒𝑛𝑔𝑡ℎ ∗ 𝑟𝑎𝑦𝑑𝑖𝑟▪Absorbed for ෬𝛼 ∈ [0.0,1.0] ≤ 𝛼▪Reflected for ෬𝛼 ∈ [0.0,1.0] > 𝛼Record absorbed rays at radial / material depth ∎Generate new random interaction length and direction for reflected rays:▪ 𝑟𝑎𝑦𝑙𝑒𝑛𝑔𝑡ℎ = −ln(ም𝐼∈[0.0,1.0])𝛽▪ 𝑟𝑎𝑦𝑑𝑖𝑟, 𝑟𝑒𝑓𝑙 =cos ෬𝑎 ∈ 0, 𝜋cos ෰𝑏 ∈ 0, 𝜋cos Ǎ𝑐 ∈ 0, 𝜋▪ Random numbers ( ም𝐼, ෬𝑎, ෰𝑏, Ǎ𝑐, ෬𝛼) generated from uniform distribution 𝑠𝑒𝑒𝑑 = 𝑐𝑜𝑛𝑠𝑡.▪ Total rays simulated: 1 × 106▪ Spatial discretization: ∆𝑥, ∆𝑟 = 1 × 10−4 𝑚Reflected ray still inside RPCReflected ray left RPCRecord as not absorbed ∎11Modeling Results: Intensity attenuationVariation of Extinction Coefficient 𝛽 (𝑛𝑝𝑝𝑖 variation)Louis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 202312▪ Intensity attenuation for diffuse irradiation stronger due to steep incident angles▪ For high extinction coefficients differences between collimated and diffuse irradiation decreaseModeling Results: Intensity attenuationVariation of Cylinder Radius / Material ThicknessLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 202313▪ For smaller cylinder(𝑟𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟 ≤ 0.01 𝑚) rays reach inner radial segments in 2ndcylinder half, resulting in increased intensity counts in inner segmentsModeling Results: Intensity attenuationVariation of Cylinder Radius / Material ThicknessLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 202314▪ For smaller cylinder radii the range of incident angles for rays reaching inner radial segments decreases▪ For cylinder a larger fraction of total volume is located in outer segments compared to plateSummary and OutlookLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023▪ Intensity attenuation related to parameter variation of RPC cylinder:▪ Diffuse irradiation is stronger attenuated in RPC structure compared to collimated irradiation▪ Cylinder with 𝑟𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟 ≥ 0.02 m exhibits intensity attenuation similar to plate▪ Cylinder with  𝑟𝑐𝑦𝑙𝑖𝑛𝑑𝑒𝑟 ≤ 0.015 m intensity attenuation is influenced by radial symmetry▪ Outlook on further modeling tasks:▪ Include additional technical reactor boundary conditions into model (e.g. distance between hot cavity and RPC cylinder)▪ Set up thermal model of cylindrical RMA unit inside R2Mx reactor15THIS PROJECT HAS RECEIVED FUNDING FROM THE EUROPEAN UNION’S HORIZON 2020 RESEARCH AND INNOVATION PROGRAMME UNDER GRANT AGREEMENT NO 823802NETWORKINGSFERA-IIISolar Facilities for the European Research Area4th Doctoral ColloquiumWP1 Capacity building and training activitiesCologne, Germany, September 11th-13th 2023Backup Slides16ChallengesReactor Design / Operation and RPC StructureLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023▪ Temperature swing operation requires reheating of reactor components after each cycle▪ Direct irradiation of RPC structure from one site results in significant temperature gradient along material thickness:▪ Inhomogeneous reduction extent 𝛿▪ Overheating of RPC front can cause higher reradiation losses and structural damageM. Hoes, S. Ackermann, D. Theiler, P. Furler, and A. Steinfeld, Energy Technol. 7, 1900484 (2019). Temperature [K]Time [s]RPC thickness17Modeling ResultsVariation of Extinction Coefficient 𝛽 (𝑛𝑝𝑝𝑖 variation)Louis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 202318Modeling Results: Intensity attenuationVariation of Cylinder Radius / Material ThicknessLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 202319▪ For smaller cylinder radii the range of incident angles for rays reaching inner radial segments decreases▪ For cylinder a larger fraction of total volume is located in outer segments compared to plateModeling ResultsVariation of Extinction Coefficient 𝛽 (ϕ variation)Louis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 202320Modeling ResultsVariation of Absorptivity 𝛼 (𝛿 variation)Louis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 202321▪ For large cylinder absorption characteristics follows similar trend as intensity attenuation▪ For smaller extinction coefficients radiation can scatter more easily out of RPC structureModeling ResultsVariation of Absorptivity 𝛼 (𝛿 variation) – Small CylinderLouis Thomas 4th SFERA-III Doctoral Colloquium - September 11th- 13th 202322▪ Rays scatter more easily out of small cylinder due to radial confinement, effect decreases with increasing absorptivityImprint4th SFERA-III Doctoral Colloquium - September 11th- 13th 2023Topic: Development of a Redox Material Assembly for Solar Thermochemical Fuel ProductionPresentation at the Doctoral Colloquium in CologneDate: 12.09.2023Author: Louis ThomasInstitute: DLR Institute of Future FuelsCredits: Stefan Brendelberger, Christian SattlerDisclaimer: This project has received funding from the European Union’s Horizon 2020 Research and Innovation program under grant agreement n°82380223 23

Development of a Redox Material Assembly for Solar Thermochemical Fuel Production

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Development of a Redox Material Assembly for Solar Thermochemical Fuel Production

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